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Well done!
You have completed Python Virtual Environments!
You have completed Python Virtual Environments!
Preview
Okay, we’ve finished a project. What now? This video will walk you through how to take a snapshot of your virtual environment and it’s dependencies so your project can be run on any computer.
Resources
Commands
To create a requirements file that holds the virtual environment’s dependencies
pip freeze > requirements.txt
To install all dependencies listed in a requirements file
pip install -r requirements.txt
To view the contents of a file in the command line
-
cat [filename](macOS) -
type [filename](Windows)
To delete a folder in the command line
-
rm -r [foldername](macOS) -
rmdir [foldername] /s(Windows)
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Whether you're sharing your project
with others or hosting it on a server,
0:00
the recipient machine needs to have
the exact same dependencies as yours.
0:04
If your project uses flask, but
the recipient machine doesn't have
0:10
it installed,
your project simply won't run over there.
0:14
We'll need a way to bundle our
dependencies with our project so that any
0:19
machine will be able to create the same
environment for the project to run in.
0:23
The first thought may be to include
the myapp-env folder since that contains
0:29
everything to do with
the virtual environment.
0:33
However, this folder is very large, and
0:38
doing this is not considered
the best practice.
0:40
Instead, we can make our virtual
environment reproducible by
0:44
creating a list of dependencies.
0:49
The recipient machine can then
install the dependencies listed and
0:52
your virtual environments
will be identical.
0:56
The most common way to do this is to
create a requirements file that contains
1:01
the dependencies of our project.
1:05
But first, we'll need to know how to
generate a list of project dependencies.
1:09
Luckily, pip comes with this
functionality ready to go.
1:15
Make sure we're in our project folder,
with the virtual
1:19
environment activated, and
type pip freeze, and press Enter.
1:24
This will print out a list of all
dependencies of this project based on
1:30
what we installed.
1:35
You may notice more than just Flask and
SQLAlchemy.
1:37
And that's because our
installation of both libraries
1:41
also installed libraries that
they need in order to run.
1:44
So we've got the list.
1:48
Now we need to save its contents
to a requirements file.
1:50
We do this by using the command,
1:54
pip freeze > requirements.txt.
1:57
Let's break down the command,
pip freeze as we saw earlier returns
2:04
a list of the libraries installed, our
project's dependencies.
2:09
The chevron is the Unix command for
redirection.
2:15
This takes the output on its left and
saves it to the file on its right.
2:20
requirements.txt is the name of the file
we want the dependencies to be saved to.
2:26
If we check our folder contents now
with ls, we can see requirements.txt.
2:33
Let's view this by using
the command cat requirements.txt,
2:40
and we can see all of
the dependencies of our project.
2:45
With this file, any machine will be able
to replicate our virtual environment.
2:51
Let's give that a go ourselves.
2:57
First, deactivate our
virtual enviroment and
2:59
then delete the myapp-env folder using
3:04
the command, rm -r myapp-env.
3:08
Remember, this folder contains all the
files needed for a virtual environment.
3:15
So with it deleted,
we don't have one anymore.
3:20
If we try to run app.py now,
3:24
We get the error messages because we
don't have those libraries installed.
3:30
Let's create a new virtual environment
with the command we already know,
3:35
python3 -m venv myapp.env,
and activate it by finding
3:40
the activate command in our
command history by pressing Up.
3:48
You'll find that sometimes,
the command history is so long,
3:59
it may just be worth typing it out.
4:02
Let's quickly check the install
dependencies with pip freeze, and
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there should be none because
it is a fresh environment.
4:10
Now, we'll use a single command to install
all the libraries and requirements.txt.
4:14
Type, pip install -r requirements.txt.
4:21
Time to break it down.
4:30
pip install, as we know, calls for
pip to install something.
4:32
-r tells pip that we're about
to provide a requirements file,
4:37
and it should install
everything in that file.
4:43
requirements.txt is the name that we've
previously given the requirements file.
4:46
Once that's done,
4:52
let's check out the installed
dependencies again with pip freeze.
4:54
And we can see that all our
dependencies are installed once again.
5:00
If we run app.py now, We get no errors
5:05
because all the required
libraries have been installed.
5:10
This lightweight text file is all a
recipient machine needs to replicate your
5:14
virtual environment on their end and
run your project.
5:19
As a result, if you're sharing your
project with others via something like
5:24
GitHub, be sure to ignore
the virtual environment folder, but
5:28
include the requirements.txt file.
5:32
If you're unsure of what that means,
5:35
be sure to check the teacher's notes
on some courses on Git and GitHub.
5:38
Congratulations on completing this
workshop on virtual environments.
5:44
You've learned how to create,
activate, deactivate, and
5:49
delete a virtual environment.
5:53
You've also learned how to install and
5:57
upgrade packages while inside
the virtual environment.
5:59
Finally, you've learned how to replicate
your virtual environments on other
6:04
machines by creating a lightweight text
file that lists project dependencies
6:09
With this knowledge, you can continue
your Python journey and create apps using
6:15
third-party libraries without worrying
about conflicts between multiple projects.
6:20
Well done!
6:25
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